If you want specific answers, provide specific questions.
On the firewall page select the chain you want to apply the block rule.
Then click “add” to insert a new rule. A pop up window will appear where you insert the details for the rule to be matched and the action to be taken (in your case, DROP or REJECT)
On the “protocol matching” line select tcp, upd or whatever protocol you want and new options will arise on the right side giving you the option to choose source or destination port (or a negation of these).