new dslite with roms in file format - how do i use these rom files?

i have a new dslite and also have alot of roms for it - these are in file format - i see alot of hardware addons for the ds lite which i assume you stick these roms onto and then run them -can someone tell me the best cartridge gizmo out there and the method for using these rom files?

I am new to this method, so my request is genuine.
I assume you just drag and drop these roms onto the memory card and then just run them - then i can play the roms - is this right?

also please post the link to the site that sell these gizmos that run the roms... im serious about this btw, and im itching to try the roms out.

Many thanks for your help!
btw im in the uk so uk links for the gizmo i need would be appreciated.

 

Part of the answer to your question is found here. Here is a good site.

 

thanks for your help dude, just bought an r4 with 2 gb card.... and there was i considering buying my first cart ;O) - not that i wouldnt if i liked the title that is, firm beleiver in try before you buy.

 

Not a prob! Cheers!