They have to be available over the internet. You can use Photobucket (one example) to upload your photos to. They have forum coding that will work for your photos to insert into your trip report. They offer a free account also.

Easiest way would be to write your trip report in word or wordpad and then copy and paste. To make sure you are using the correct photo code (image tag) try it in the testing forum. Then you can insert your code for each picture in the trip report prior to doing the copy and paste.