how to start the configuration (newbie)

hello help it is the first time I use a mikrotik router.
I have many doubts.
I am going to balance 3 internet lines. create 5 vlan, and limit bandwidth to vlan. activate dhcp for each vlan. what do I start with first and how. mikrotik’s os is new to me.

Read this:
https://help.mikrotik.com/docs/display/ROS/Getting+started

I would start with connecting the primary ISP first by itself.
Create the vlans, dhpc etc.
Adjust the firewall rules appropriately (minor changes from default).
Then post your config here to see how you are doing.
/export hide-sensitive file=anynameyouwish

Then tackle adding the two other ISPs.
Then tackle load balancing them.

Lastly look at limiting bandwidth.