The most soul-crushing part of TBS. Getting anonymous feedback from your peers. I always wrote mine with the mentality if these weren't anonymous, I would be okay with my platoon-mates knowing what I had to say about them. People often used these to unleash anger and vitrol on people. Why not just use these for constructive criticism?
You'll have three peer evaluations. You'll give feedback on everyone in your squad, both an improvement and sustainment. Then you'll give a Top 5 and Bottom 5 in your platoon, with an improvement and sustainment as well. These can be from outside your squad, but a lot of people know people in their squad better than those outside, so there will often be overlap.
Your SPC will read these, and take it with a grain of salt. I'm not sure how much these evaluations factor into their own evaluations. I believe they might just use these to corroborate what notions they already have of you.
Don't fret. Just take them as a learning experience and read them with a glass (or bottle) of wine.