I'm confused about how to play them-I know an acciaccatura is a crushed note, thats played really fast but dunno how to play an appoggiatura! help!

Normally an appoggiatura is just an on-beat dissonance, I think, which can be written small like an acciaccatura but without the line through the stem but doesn't have to be- it can still be called an appoggiatura without the special notation.

I think.

So that's not definitive!

An appoggiatura usually takes half the value of the main note it's with. If you had an appoggiatura before a crotchet, you'd play them both as quavers. If you had one before a quaver, you'd play both notes as semiquavers........and so on.

But if the main note is a dotted note, theoretically you're supposed to make the 'little' note take two-thirds of the value of the main note! So if you had one before a dotted minim, the appoggiatura note would be held for a minim and the main note only for a crotchet.
In practice, this 'two-thirds-and-a-third' proportion very occasionally just doesn't sound right in the context of the music, so it can be 'tweaked' a little if necessary to make it sound more musically satisfying!