I had a lovely date recently and i would like to recommend them. Anybody know how to do a testimonial?

Yes :-)
First, to make a Testimonial for someone, you MUST be on their 'Friends' list.

Then, you go to their profile and click on the orange link
for 'Add Testimonial.'
~~~

You may NOT be able to see your testimonial on their profile
page if they have turned off that feature. (To turn ON that
feature, which is on the 2nd page of profile edit:
From a mobile device:
http://m.mingle2.com/edit_profile
From a PC:
http://mingle2.com/user/edit_profile)

>>>Edit Profile>>>(2nd page, hit 'continue after 1st page)>>>Show Testimonials

(This is also the place to edit for your 'Friends' list to show
or not on your profile.)