Can i get ios 4.3 on the iphone 3g?

I bought an iphone 3g the other day from ebay and i tried downloading apps and it doesn't let me download any i have tried atleast 50 and it keeps saying to upgrade my IOS is this possible and if so how do i do it?

Connect to iTunes with a computer… The screen wil pop up that an iOS download is available… So click on d option download n update… It wil tke sum tym bt wil b dne…

I'm sorry, but the iPhone 3G stopped being supported when iOS 4.3 came out. There's no way to upgrade to iOS 4.3 unless you find more obscure methods then you might find something. You should've gotten a 3GS at least.