There are many tools which you can login a server remotely . Below you can see how can we login with putty.
In putty tool enter your hostname or IPaddress of server at below highlighted tab . Then hit enter or click on open
Then you will get prompt to below screen . You can click on yes and it will ask you only first time you login to server . once you click yes it wont ask you for next login as your computer saves the host key .
After that enter your login credentials as shown below .