Sounds like a GCSE exam question, one where you have to write a massive essay in exchange for a single statement!
how easy depends on what is already there. If you have a little cavity carcass, with a base, especially for an oven, it will be easy, just electrical connections and a few screws. However, if there is no cavity shell, you will need to install bracket runners on the sides of the adjoining cupboards and place the oven on this.
IS IT GAS? If so, you MUST get a CORGI plumber to get it connected.
I could go on, your question was very open. Would you care to elaborate?