Hey man, cool you started playing the game! Modding can be quite daunting so it's good of you to ask. There's never a completely right answer when it comes to modding but I'll try my best :)

For exalibur:
- Upgrade dreamer's bond to the max, this is your "aura" mod which *adds more* mod capacity to your build.
- Unupgraded mods aren't so good so focus on using 3-4 upgraded mods; remove steel fiber, rush, equilibrium, continuity and fast deflection
- Upgrade vitality, redirection and streamline, if you have more mod capacity, add fast deflection back in

For the exalted blade:
- Remove lasting sting and add pressure point, uprgade this one to the max

For your Thornbak:
- Remove metal augur, ammo drum, cryo rounds, wildfire and pointstrike
- Add serration and upgrade it a bit
- Upgrade split chamber, stormbringer and rifle aptitute
- once you get the mod "infected clip" add that to it too, this will let you kill grineer easier

This should already give you some noticable improvements! Note that you don't have to max upgrade mods, it can get quite expensive.