The instructions are on page 11 of the manual that should have come with your phone. You push the cover release button on the back of the phone, slide the cover up to remove it, lift the battery out to uncover the SIM, then press the tab above the SIM to release it and slide the SIM up and out. Really, it takes about 10 seconds.
Slide the back cover down and off, then lift the battery from the top to remove it. The SIM holder is below (not beneath the battery.) Slide the SIM into it with the gold contacts face down and the cut corner at the upper right until it clicks, then put the battery back in and slide the cover back on. Takes another 10 seconds.
That is correct. They do not care what phone you use with your SIM.
R's,
John