Open your audio production program, ideally Sony Acid.
Set the key and tempo at which you want to work. Sony Acid defaults to the key of A and 120 beats per minute.
Browse through the folder that contains your loops with the explorer window in Acid.
Take note of the key and tempo of each loop. Acid will automatically shift the pitch of a loop up or down to match the key you set for your project. It will also adjust the tempo faster or slower to match the project tempo.
Double-click the loop you want to use.
When the loop appears in the sequencer, click the Draw Tool, then drag the pencil icon horizontally to "draw" the loop into the sequencer.
Repeat Steps 3 through 6 as many times as necessary.