Hi and welcome.
As fluttermoth quite rightly pointed out the beginners section is a must read. It can all seem quite daunting at first, but everyone is here to help and once you have your head around the basics, you should be fine.
Just for a little bit of info, I'd recommend not adding fish at this point, otherwise you'd be in a fish-in cycle, which requires careful and consistent monitoring of your waters parameters, such as ammonia, nitrite, nitrate etc and a large number of water changes.... you'll find info on this in the above section, any questions, feel free to ask.
What you'd be aiming to achieve is to go through a cycle in which your filter builds up 'good bacteria' which enables it to break down fish waste, excess food etc. You can do a fishless cycle by dosing ammonia to your tank and recording the results you get week on week, you would need a reliable testing kit, preferably liquid. This process can take a number of weeks, it's been a long time since I had to cycle my tank but I think somewhere between 6 and 8 weeks is the norm for the process to be complete. It does sound a long time, but fish-in cycles can be detrimental to the fish and quite stressful if you don't keep on top of things, multiple water changes everyday can wear you down week after week and I'd always recommend fishless cycles where possible.
I'll try not to overload you on info, but please do have a good read of the beginners section, which explain what you'll need to do in order to have a nice introductory in to fish keeping.