If you want change the directory your bash prompt is starting in, you can edit your .bashrc file. At the bottom, add:
cd ~
This will go into your home directory. (you can actually do just cd, but I it’s clearer to add the ~ IMO)
To edit, you can use vim. If you don’t know how to use it, you can always use nano for the time being, but you really should have a look at it, it’s really powerful.
$ nano ~/.bashrc
This will open nano in “full console”. At the bottom, you have the few commands you can use (^ means control) Do your changes, hit ctrl+o to save the file (write the file). It’ll ask you where to write, by default, it’s the right location, just hit enter and the .bashrc file will be saved. Then, you can press ctrl+x to exit.