The first thing you need to do when setting up a blog is to choose your blogging platform. There are many out there including WordPress and Wix. You will also need to choose a domain name and a hosting company. Many domain companies also offer hosting but you need to check the packages carefully to insure that they will be able to handle the amount of traffic you expect to get and also that they are reliable. Reading reviews of the hosting company is vital to ensuring that you find a good one. There is no point in having a fantastic blog if it is going to be offline often.
The next thing to do is to think about the design of your blog. Many blog creation sites such as WordPress have thousands of themes which you can download for free, or you can hose one of the paid for ones if you want a bit more flexibility. If you have a specific design that you want then you will need to contact a web designer to get them to create a bespoke theme for you. Once you theme is live add in any plugins that you may need such as the SEO and social media sharing options. This is now the base for your blog posts. You will need to start adding relevant and interesting blog posts as often as you can and also look at promoting these of sites such as Facebook and Twitter to build up awareness.