Am operating Tour services in Tanzania can anyone help me how to advertise?

It depends on your marketing budget. If you have a website, online marketing will be a way to go by doing PPC, submit your site to search engine and other industry related directory, write articles about your company services and submit to article directories, write a post or pay someone to write a blog post, word of mouth and many more. So, you have the power in your hands to advertise in many ways.