This is pretty long, the first bit is an explanation and the last bit are the answers.
To conjugate verbs you first remove the infinitive ending and then add the ending that matches the subject.
Here is a chart of your first problem:
You sing
Cantar (sing)
Subject: AR Ending:
yo o
tú as
usted a
el, ella a
nosotros amos
ellos, ellas an
Using the chart "you sing" becomes "tú cantas".
As you can see we removed the infinitive ending (cantar), and then we input the ending (as) that matched the subject (tú). So then cantar becomes cantas to match tú.
Anyways, here are the rest of your problems:
5. todos ustedes dibujan
6. nosotros esquíamos
7. ellos bailan
8. nosotros usamos
9. tú trabajas
10. ella habla
If you have anymore questions just ask. Hope this helps!