Doing EQ by hand sounds pretty complicated but it can be pretty intuitive once you've done a couple measurements and tweaks. Basically you are adding one filter per peak to lower them, so that the green line becomes smoother and closer to the yellow line.
Basically, to handle peaks by hand, here's what you would do:
Find a peak (as
@kyuu points out), note the frequency. Look at the difference between the top of the peak and the yellow line. For the lowest peak, this would probably be 33ish Hz and 13dB.
In the EQ software (Peace or EQAPO or WiiM or MiniDSP etc.) make a "peaking" filter (easy to remember) with the same frequency, but -13dB gain instead of +13. You are lowering the peak here.
There is a third setting, "Q". This stands for the width / sharpness of the filter. Usually for correcting bass, Q will be between 1.0 and 2.0. Higher numbers make sharper peaks or cuts. Setting Q is somewhat trial and error, but the goal is to make the filter match the width of the peak in your measured response. It might take a few tries.
If the software shows you the EQ curve, you can use that to adjust Q by eye, otherwise take another measurement and adjust based on the result.
WiiM has the same functionality as this, it's pretty standard in any EQ software.
Basic room correction software (like on WiiM or the REW utility) automates this process, but doesn't do anything you can't theoretically do by hand. It works on exactly the same basis, but tries to solve for the best-fit curve it can using a set number of filters.
You can also sort of try to fill in dips the same way, but it doesn't work as well due to the acoustic nature of dips vs. peaks. Peaks are 1+1=2, so 0.5 + 0.5 = 1. But dips are 1-1=0. If you adjust it, 2-2=0 and 0.5-0.5=0... so adjusting dips doesn't work the same.
IRL dips aren't usually cancelled truly perfectly, so you can fill them in a little, but asking your amp to do +10dB at low frequencies is typically not fun for the amp, so they're hard to deal with using EQ.
More advanced room correction software like Dirac, Audyssey or Trinnov does fancy things with phase and even actively cancelling some reflected sound to further improve sound... but you get pretty far (maybe 80%) by just leveling out peaks.
Anyway, it looks like you have some pretty considerable peaks in your response... it's likely that your Klipsch speakers were exciting the same modes. Once you correct the dips you're probably going to feel even more of a lack of bass. But, once that's done, don't be afraid to add a low shelf to the whole thing and boost the bass back to where you like it. Once you've done that, you'll have smooth bass and the correct quantity, with each bass note coming through at the correct volume, not the semi-random in-and-out sound you get with uncorrected bass.
