How to add "two" transitions between clips in Premiere? I am very new to this video editing, so sorry,...

I actually want a transition that takes longer to undip from black than to dip to black.

I wanted to add two transitions, one at the end of the first clip and have the transition stop at 50% and then another one at the beginning of the next and have it start at 50% and then adjust the time the transitions take.

It turns out one can only have one transition between clips. Which makes sense, but does not explain how I should proceed.
I am unclear on what you are asking. So you have 2 clips on your timeline and you want to have clip 1 dissolve but only halfway? That's your opacity. So just click on your clip in the timeline (next to the clip name I believe there's a twirly) and you should be able to select motion, or opacity. Click opacity. Then adjust it with keyframes.

Then go to your second clip and start your first keyframe at 50% and then further along the timeline take it back to 100% with another keyframe?

I hope that helps.