Code:
|\
| \
A | \ C
| \
|___x_\
B
The best thing to do will be to post the problems here that you are struggling with, but I can fill you in on the basics.
Observe the triangle above.
C is the hypotenuse of the triangle, and is the angle opposite side A.
Sin
The sin of an angle is equal to the side opposite the angle, divided by the hypotenuse.
Cos
The cos of an angle is equal to the side adjacent to the angle, divided by the hypotenuse.
Tan
The tan of an angle is equal to the side opposite the angle, divided by the adjacent angle.
You have to know these identities by heart.
Post questions of specific problems you do not understand too.