Im new to all this lol

Ok so im new to moded cars and its something I want to get into so bear with me and my complete lack of knowledge.
So I drive a mk6 fiesta lx 1.25, bottom line I want to know what engine swaps can I do e.g. 1.6 or an st engine or something. And before you say its not worth it or its not a good car anyway I already know this but still its my car and I want to make it the best I can so fire away with ideas for me to do. Btw in terms of appearance I know all about that its the actual engine/performance side im clueless about.