Here is a brief tutorial on how to add a blog post to your WordPress website.
1. Log in to your WordPress Admin account. (this link, user name and password, will be provided by your web developer)
2. Click Post > Add New
3. Add Title
4. Select the Visual Tab
5. Enter Text, Links, & Images
6. Click Add Media to add an image/media to your post.
7. Click > Insert into Post
8. Add Categories – Tags
9. Optional – Set Featured Image
10. Click Publish
NOTE: You could Save the Post as a draft to access it at a later date. You can also Preview your Post before you publish it live on the web.
Here is a good Tutorial Video