[IoanaD]

Both of these reactions take place in the presence of an acid catalyst. For the second reaction I believe we get a cyclical compound like cyclic acetal (except instead of one of the oxygens there's a sulfur). Correct me if I'm wrong,
For the first reaction I'm kind of stuck... I'd really appreciate some enlightenment :S

[orgoclear]

for the first one, think about cleavage of the ester.

[azmanam]

the first one isn't an ester, it's a hemiacetal.  Think of what happens to hemiacetals under the reaction conditions

[IoanaD]

AH! i don't know how i could miss that..hemiacetals react with an alcohol in the presence of an acid catalyst to produce an acetal! Ok, thanks for the eye-opener. I had the lecture on this today...
Is this correct for the second one?

[orgopete]

Yes, and if you apply the same mechanism to the first one, you should arrive at the correct answer for it as well. Hint, you are half-way there.

[IoanaD]

So the first one would be something like this...i'm sorry, i've just begun working with these reactions.

[Scatter]

Don't apologize, you're doing great!