If all the pipes and electrics match up so you do not move any pipes/wiring then it should realitvily easy, even if neither of you have done it before.
Advice, shut off water and electricity when installing the dishwasher (that is usually the #1 mistake of DIY projects). Then take your time installing and follow the instructions. After installed run it and make sure there are no water leaks which could lead to problems down the road. If there are leaks pull it out and see if you can figure it out (usually very easy to figure out what needs to be done to solve the issue).
Ask to see the installation instructions before you buy, ask questions if you have any about the instructions. If it simple to understand with clear pictures and instructions and seems that you can do it go for it, buy and install yourself. If you have family/friends that live near by ask if they have installed a dishwasher before and see if they can come over and help/oversee what you are doing. We do this all the time and learn so much from them.