really, this is the sort of thing you should be working out yourself, but ok.
FL sends are hard routed to the master, so dont use those. in fact, dont use those for anything lol.
so lets say your bass is going into mixer channel and the channel is called "bass" well rename that to "bass in"
now create 2 new mixer tracks to the left of it, so you have 3 tracks
name them like this, left to right:
now, by using the little orange arrow under the mixer track faders, you route them like this:
bass in --> bass fx
bass in --> bass mix (yep, "bass in" is routed to both of these)
bass fx --> bass mix
bass mix can be routed wherever you want. this is your new main bass mixer track. just be sure to check that bass mix is the only track going to anywhere else, so you'll need to select the other 2 and make sure they're not going to the master.
your synth should be going into Bass and then gets split before going to Bass mix, so now you just have to select Bass fx add an eq (or bandpass filter) and distortion. another good combo for this track, is eq and reverb, gated with love philter, but thats more for rumbling sub bass stuff
i reckon you should get love philter on bass mix, though, as it can be used to make quick sidechain effects, using its volume env. that'll let you try out different curves, without messing about with a comp.
oh yeah, and your sc should be happening on bass mix
thats the technique you'll probs be using a lot when you get more into it. even for things like routing hihats and the top end of clap /snare etc
hope that helps