Learn English – use ‘I wish I were there’ in this situation

I'm not totally sure I grasp what you're asking, but are any of these phrases along the right lines?

Basically, you've written a letter, and want to ask someone to give you their opinion on it?

• I wrote her a letter. What are your thoughts on it?
• Would you like to read the letter I wrote for her?
• Can you give me your thoughts on the letter I wrote for her?

Or maybe if you're asking someone what they think about you writing a letter, before you write it;

• Do you think I should write her a letter?
• I could write her a letter, what do you think?

Also, "How about I wrote her a letter?" or "How about I write her a letter?"

• Wrote = past tense, so you can't use this to talk about doing something in the future.
• Writing = present tense, "I'm currently writing her a letter.".
• Write = correct, future tense. "How about I write her a letter?"

'There', better call it 'introductory there', assumes the person & number of the WORD which seems to you to be the subject, but for all practical purposes , THERE takes its place. As: 1) There was a king. 2) There were kings Also keep the concept of "Singular &Plural" of that 'PSEUDO SUBJECT' clear in your mind.