Example: Dear Sir/Madam, I wish to hold a seminar on..........[ Write your topic here] on .........[ Write the month or date] at your university. Please let me know if this is convenient. I look forward to your reply. I can be contacted on [ write your mob phone number here] at your earliest convenience. I can supply more details if need be. Yours sincerely, Write your name and surname here

It's not clear if you are offering a seminar, or if you want them to provide one. Either way - the most important thing would be to find the right contact - someone who has an interest in the subject. Otherwise - your request would probably just get binned. Also - don't use very informal language (e.g. wanna!)