I'm wanting to run my wire underground to my garage and don't know what wire to use and don't know if I should use metal or plastic conduit

Hi fella,
I think in all honesty, Due to the fact there are numerous questions to be asked before the correct cable can be recommended, IE; How deep are you going to bury it, how much load is the cable going to have to cope with, Are you going to spur off a socket (NOT recommended) or is it going to be a direct feed from the breaker board etc, etc... I would strongly suggest you visit an electricians trade counter like 'city electrical factors' or 'edmunson electrical'... Look in the yellow pages for your local trade counters.
You could install anything from 3.5 twin & earth fed through either sturdy poly-pipe or 20-25mm metal conduit right up to 'Armoured Cable' which doesn't really need any containment.
Not only will you get sound professional advice, You will save yourself a fistfull of dollars compared to buying from a high street hardware shop...
;) SLIM;)

im wanting to run my wire underground to my garage and dont know what wire to use and dont know if i should use metal or plastic conduit

Need more information.

Example:

1. Plans for garage (reason for wanting power)
2. Distance to garage
3. Main service rated panel size