现在想着报志愿，怎么说？

I'm considering Filling in a college application form
Filling in a college application form is no trivial matter, you must consider it carefully.
填报升学志愿非同小可，要慎重考虑。

I'm thinking about filling the college application form.

I am thinking of filling in university application form.

I wanna fill in the college(uni) application form