Can some help me figure out the best way to make this work?

From the diagram below, i want Host A and Host B to be printing through Window xp that share the internet connection before the Mikrotik.

Detail explanation will be highly welcome.

Am not good in routing traffic.

Where is your problem?

Add the IPs on the MT: Add the internet route: Set the MT as default gateway on Host A and Host B.

Then on the xp box you either need to set a reverse route or use NAT on the MT:

/ip firew nat add chain=srcnat out-interf=ether1 action=masq

what i want is for host A and B to be able to print document through the printer machine installed to the window xp.

They can surf the internet effectively without issue.

Can someone respond to my request please.

what i want is for host A and B to be able to print document through the printer machine installed to the window xp.

They can surf the internet effectively without issue.

Probably you need to connect to printer machine by IP address not by computername.
Can you open \\192.168.0.1\ on Host A or Host B?

no

Host A and B are not connected directly to window xp.

Do you have firewall on your Mikrotik that blocks access to File and Printer Sharing on printer computer?
If not, you should be able to access shares on that machine via the router.

Yes.

But how can it be allowed

Don't drop it? By default the firewall permits all packets. So if the packets are getting dropped, they're getting dropped because you told the firewall to do so.

If you need specific help with your specific firewall configuration - that's going to be impossible unless you share your firewall configuration.