I'm not sure where's the best to post this, but here goes...
For my GCSE controlled assessment composition I've written a duet for violin and cello, and pretty much all i have to do now is put in the fingering. As a violinist the violin fingering is fine, but i'm not really sure how i should do cello fingering, i know it's different to violin. Unfortunately I'm not allowed to take the music out of the room but I am allowed to ask some general questions and work it out for myself. The piece is in A minor so I think what would be most helpful would be for a cellist to explain the fingering for an A minor scale, going as high as possible? Or anything equally helpful. Thank you!

I'm not sure how much you know about cello fingering to start with so forgive me if I say things you already know.

Basic cello fingering is 1,3,4 which on the G string will give you A,B,C (ie from the open string tone+tone+semi-tone), the beginning of your A minor scale.

On the D string with 1,3,4 you will get E, F# G. If you want an F natural use the 2nd finger instead of the 3rd.
Similarly on the A string to get a C natural use the 2nd finger (the 3rd will give you C#).

The problem comes with the G# on the D string (and this is where the fact that I'm not a cellist becomes a problem). To get from F# to G# you would do a forward extention which is marked by a "x" by the finger number. In practical terms, you put your 2nd finger where the 3rd finger would usually go and then if you put your 4th finger down you would get a G# because your fingers have moved up a semi-tone. You would notate this "2x." I'm not sure what you do if you want to do a harmonic minor and go from F# to G# - I'd be inclined to say that you change positions but I'm not sure.

Likewise, to get the G# on the G string you could go into half position like on a violin or, if it's just for the one note you could do a backward extention notated "x1"

The space between the fingers (ie semi-tone between each finger) is valid in the higher positions (although I don't know what you do once you start using thumb positions) as is the principle of forward and backwards extentions to "gain" a semi-tone in either direction.

If I compare my own experiences on a violin to my daughter's on the cello, I think cellists shift position more often (but this may just be an impression).

With a bit of luck you'll get a "proper" cellist along soon

Ok, here's the fingering for A minor (melodic), two octaves.

Starting on the G string in 1st postition, the fingering starts 1,3,4. This gives you A,B,C. Moving onto the D string, and still in first position you need to play the D, E, F# and G#. This is achieved as follows: 0,1,x2,4. As kerioboe has rightly mentioned, there is an extension required to get the F# under the 2nd finger. To fully explain:

Play the D as open, then first finger on the E, EXTEND to play the F# with the 2nd finger, then the G# is played where it naturally falls, under the fourth finger.

Then complete the first octave with the open A. The B and C are played with the 1st and 2nd finger in first position. After this, it kind of gets a little choppy, in that you don't really sit in any of the straightforward positions for the rest of the octave. The D and E can be played with either the 1st and second, or the 1st and 3rd, whichever seems more comfortable.

Bear in mind that, Cellists can play Amaj 2nd octave 0,1,2 -1,2 -1,2,3 or 0,1,3-1,3-1,2,3, depending on how they are taught, and what feels comfortable for them. It's a little different for Amin as you have to deal with a Cnat rather than C#, so 0,1,2 is more appropriate and the player might not want to swap between 1,2 and 1,3, judt for consistency when playing a scale.

This part of the scale falls between 2nd and 3rd position, it would depend on the piece as to what a player would do at this point.

The top part of the octave moves further up the A string, first finger on the F# then 1,2,3 for the F#, G# and A. Again, this falls between what you'd normally call 5th and 6th position on the Cello.

As this is the melodic, the 6th and 7th will be flattened on the way down, so you're looking at Gnat and Fnat. In both the first and second octave, this requires a subtle change. Down from the 2nd octave A, you have to stretch back a tone to hit the Gnat with your second finger, then a tone again to hit the Fnat. It's not a huge stretch, I wouldn't expect to see it written as an extention really.

The first octave you loose the extension and play in first position, the 4th on Gnat and the 2nd on Fnat. Written out the whole thing looks like this:

Up - (G)1,3,4, (D)0,1,x2,4, (A)0,1,2,1,2,1,2,3
Down - (A)3,2,1,2,1,2,1,0 (D)4,2,1,0 (G)4,3,1

I hope this helps a bit and isn't too confusing to interpret (I read it back and it loks a bit of a mess).