How do you enter long codes in the AR card manager?

Maybe get a manuel from the shop you bought it from.

To do this is you are running Vista, do the following:
1. Right click on the Action Replay Manager and click Run as Administrator.
2. You will need the administrator's password of the computer or if you are the administrator, then click continue.
3. At the top of the code manager, click the icon that looks like a DS cartirage and says Software upgrade. 4. It will download the new firmware, which lets you copy and paste codes. 5. To copy and paste codes, copy a code, and on the Action Replay manager, go under the Nintendo DS area and drag your game to the My codelists section.
6. Right click on the game, eg. Pokemon Pearl in the My Codelists section, and click Add New Cheat. 7. Name the cheat, paste the code, and click Ok. 8. When you are done putting codes on, drag the game back to Nintendo DS.

I hope this helps.

I read at nintendo.com it's not compatible with vista only xp. If it's true try what he said but you should look it up first on google