Pregnancy tests come with much better directions than I could offer, but it's pretty simple. You usually pee on a stick, wait two minutes, and then see what the stick says.
Some test may have a one line 'no', two lines 'yes', while others simply remain blank if you are not pregnant and form a pink circle if you are.
Each test has different symbols, so it's best to make sure you absolutely know what your particular test means. Otherwise you could think you are pregnant, and not be.
Tests can be a bit pricy, so it's best to make sure you take it when appropriate. Again, the label will specify when it can be taken and be effective; for some, it's as soon as you miss a period, while other require you to wait two weeks.
Basically, find a drugstore without many customers and spend some time reading the back of boxes. Pick the test that seems best for you, then read the intstructions carefully once you open it. Tests can be wrong, if you have missed a period and the test says you are not pregnant, wait a week. if your period still hasn't come, take the test again.