Three ways to achieve IR effects:
1. On a DSLR, buy an IR filter that will fit your lens. Downside is that they block out visible light. Which means metering and focus won't work. You also have to guess at exposure times. Be very careful not to look at the sun through them, since all the IR light is passing through and could fry your eyes (not positive about this last, but I wouldn't take chances).
2. There are specialty shops that will modify the sensor on your camera (more specifically the filter that the camera maker installed to block IR light). Digital sensors are very sensitive to IR light, so without a blocking filter every photo would have the surreal IR look. Remove this filter and voila, white grass and leaves. It's possible to convert both DSLRs and some point-and-shoots. Once you do it though, the camera can ONLY shoot IR. So make sure you really like this style of photography.
3. It's possible to fake the IR look in Photoshop.
IR photography
Hope this helps.