1.
https://www.dyndns.com/account/services/hosts/add.html
2. Fill out the required fields (hostname, service type, etc..)
3. Leave Wildcard UNCHECKED
4. Keep service type as: Service Type: Host with IP address
5. Enter your current ip address (not local) in the box. (It also says: Your current location's IP address is "xxx.xxx" etc... so you can copy and paste the ip there into the box)
6. Leave IPv6 Address blank
7. Leave Mail Routing UNCHECKED
8. Click Add To Cart (don't worry, it's free $0)
9. It will say to register or login to continue checkout, so register then go back to your cart when thats done
10. When you are back to your cart, click the blue button (Proceed To Checkout)
11. Click Activate Services after that page
12. Now it should be activated, but you have to download the ip checker tool, this tool automatically knows when your dynamic ip changes every day so you don't have to change your sa-mp server ip everyday. (This is why stuff like no-ip and dyndns come in handy when you have a dynamic ip, so you don't have to keep changing everyday!)
13. download the tool here:
https://www.dyndns.com/support/clients/
Read through that then download it.
When downloading that is complete and its installed and you open it, you will see your hostname and see your ip and username etc... (unless you have to log in first because I forget)
Now you can add your ip you made on the website with the .info, .biz, .org etc... extension that you have with the port at the end to your samp server list.
*Note if it says retrieving info, you might have to restart your computer for it to work.
Thats it, enjoy, let me know if there are any problems.