A blog hop is basically a widget that allows bloggers to add their blog to a list. This linky can be used on the host blog or multiple blogs and creates a list of sites to visit. Rules can vary from one hop to another as some hosts require you to put the Blog Hop banner on your post/blog where others have no rules at all. Basically you just add the link to your blog post to the linky list. It's good etiquette to visit other participating blogs and leave a comment. make sure your comment is sincere and not spammy though. Comment on their post and let them know you're following the blog hop. As they are too there is no need to ask them to visit your blog as they will already see your link on the linky list.