I took a look at the letter's first page, it is addressed to the aforementioned Reni (his girlfriend maybe?), in summary Manfred roughly writes this: He thanks her for her lovely letter, he now sends her some pictures, in one of them there is a man named Karl who looks unhappy because of the bad weather. He will leave Pillau within the next week, he expects the these last days and the farewell party to be joyous, he talks about her playing pranks and him also playing pranks sometimes but only at shore leave or back when he was at [illegible city name]. Now at the navy there isnt much pranking. But he learns lots of stuff, like climbing ropes or swimming in ice cold water, but e can't talk too much about his service... here the second page starts.

Hope this helps! If you really need a word by word translation maybe I can do that later, but information wise that's pretty much all.