Welcome to Simviation, Domj! Hope you find this place as useful and enjoyable as I have over the last many months.
First thing, don't panic! Flying has some definite learning curves to it. What may seem impossible today will become second hand after some study and practice. That your landings now with the passenger airliners are too fast is not so bad. When I started trying to land those aircraft in FS, I used them to dig big holes in the ground!

Now, I am going to be a bit of a maverick here when it comes to advice. Almost all of my fellow SimV'ers (most of whom are smarter and more experienced than I am, but only a fraction as dangerously dashing . . . or something) will tell you to spend many, many hours practicing with Cessna's and other small aircraft, go through each of the tutorials provided with the program, and learn all the basics first. That is what I did, and it sure did help! But, I am not going to tell you to do that. Nope. I am just going to skip straight ahead to landing big, big jets. See - total maverick (or nutcase, or wacko, or something).
Just read this
here.
You're like, "I already told you that I can get lined up with the runway!" I know, I know! But, jsut in case you hadn't been using ILS, that will be a big help. Because, if you aren't having to worry about manually staying on the glide-slope, you can concentrate on other things, like speed. Plus, that guide also mentions speed management.
A handy thing is to let the autopilot manage your speed. At about 20 miles out (provided the approach allows for it), I slow down to around 200kias. By 15 miles out, I am down to 175kias, and I have out 10 degrees of flaps. At 10 miles out, I am down to 150kias, I am at full flap extension, and I have my gear down. Between 10 miles out and 5 miles out, I set my auto-brakes (I usually use 2 on the Boeing and Medium on the Airbus) and I set arm the auto-speed brakes (don't actually raise the speed brakes, just arm them!). At about 300 feet AGL, I turn off all of my autopilot functions and manually bring the aircraft in the last little bit. At this range, if you maintained 150kias, you can set the throttles to zero a bit early and coast into your flare and landing and that will automatically slow down around the 140kias that makes for a good 737 landing (or so it seems I read; could be even slower . . . I know a nearly fuel-empty A-321 can land at a ridiculously low speed).
OK, that was a quick and dirty explanation that gets you landing big boys without first flying for a couple of years in Cessna's. Not that there is anything wrong with that! Flying the little prop planes will teach you ever-so-much more than pushing the airliners around in FS. But, since they really do behave differently, I decided to just skip to the chase and try answering your question directly. If you have any more questions, feel free to ask.

To all you seasoned SimV folk out there, don't take my virtual wings away, ne?

All the best,
Darrin