Trying to get internet on both of my computers at...

Question

Just purchased a rangeplus wireless router and want to get my other computer to work on line with the router. I was told I need either an ethernet cable or an adapter. would rather have an adapter but don't know which one to get and how do I install it? please let me know if this would be an easy task or would I have to bring my computer in for this and also what the price would be for the cable and the adapter. Thanks