at this stage if something doesn't work then getting it to work is likely to be a very difficult task.
even if you were to get it to work the majority of the games people seem to want to see 'working' these days would run very, very slowly, to the point where most end users would still consider them to be non-working.
a large number of the remaining tasks aren't even something a software developer alone can achieve, a significant number of the more difficult remaining tasks require extraction of internal code from MCUs etc.
as Howard has stated, if you have no real programming skills then the chances of you making something work that doesn't work is very low. The team does already have a number of members with no / minimal programming skills, but they tend to work on improving the documentation, or doing 'grunt' work by following refactoring patterns etc. without making any real progress when it comes to getting things working.
even if you can program it's not always enough to make a real difference when it comes to the emulation of things, again the team is full of people who can program, but appear to lack the knowledge or motivation to actually do the reverse engineering work to bring systems up to working state, while this is useful for maintaining a healthy project it's only going to take you so far.
I'm not trying to be negative here, because we really do need more contributors, people who are really good at coding (and could do something revolutionary with MAME) and people who have the motivation and ability to figure out even the most undesirable of systems as well as people with really deep knowledge of the inner workings of systems we're trying to emulate (especially on the MESS side) but you make it sounds like you have none of those skills.
state what you're interested in and I can explain the problems with emulating it if you like...