Need Help-Updating S4 (From 4.2.2 Rooted)

[spyder]

Hi There.
OK, QUICK background. I bought this phone when it came out. Screen broke 3 weeks later, JUST fixed it now. Also, I have been out of the Android loop for about 2 years (NO, not iPhone....had to go 'Away' for a while...ugh, nothing gross or horrible)....Anyway, I just got the phone running/fixed..Here is info:
1. SCH-I545 (Was Verizon , now on Straight Talk)
2. Android 4.2.2
3. Baseband: I545VRUAME7
4. Kernel: 3.4.0-690088

I want to eventually get it to Lollipop (rooted). If I have to step thru KitKat..I wouldn't mind trying it. Everything I see is from 4.3 and I don't even have that.

I am sorry. There was a time 2+ years ago when I was quite on top of this stuff. I've really slipped and would REALLY appreciate the help. I prefer to not lose root, although if I can redo, that's fine (or hide it?).

As pathetic as it sounds, I was hoping for someone to give me a little walk through....I've been reading but I'm too far behind what it on the boards now.....

THANK YOU ALL.....I'm trying to get back involved and look forward.....