I am trying to upgrade this dell desktop to a 1 gb graphic card but I am new at this. If the tech specs for the computer say that it takes a PCI express 1.0 x16, can I put a PCI express 2.0 x16?? And what order do I install graphics card then driver??
Dell offers four versions of the Optiplex 745. What upgrades we can offer depends on which version (Mini-Tower, Desktop, Small Form Factor, Ultra Small Form Factor) of the system you have. Regardless of which version you have, there's no guarantee that an update is even possible.
You should be good to go with a low-end, low-profile PCI-E 2.0 graphics card. Something like this Jaton Geforce GT620 PCI-E 2.0 graphics card should work in your system without putting a strain on your 200 watt power supply. Understand, this is by no means a gaming graphics card. This system cannot handle a gaming class graphics card, but any discrete graphics card will work better than just the on-board graphics.
Edit: Also, install the graphics card and then install the drivers for the card.