First you have to download Havji. You can search it on google.com.
Now that you have it. Find a vulnerable site by searching up inurl:index.php?id= choose one that vulnerable.
Once you find one put it in Target spot Like this
Picture than click analyze
Than this should show
PictureThan you click Tables
Than you will see this
PictureThan you click get db
Than you should see this
PictureThan you click information and test than click get tables
Than you should see this
PictureThan click User Det and get column
Than you should see this
PictureThan you click the username and pass and than get data
Than its should look like this
PictureNow you just have to find where the admin login at and you would be in
And Thanks for coming
Credit:
Havji
Unkn0wn
Lilj98
AngelX
etc
Admin
Please commant if it help