Cant use original password, after hash (pgcrypto) - node.js

Question

I have succeded in hashing my password for my admin user, the problem is now that i can no longer use the original password to log in (no errors, exept the correct response for invalid passwords). I am able to to select the user table and just copy in the hashed password from PGadmin (using PostgreSQL). Im not really sure where to go from here.
1. I think i have to get my login form to recognize the hashed password, and somehow match it up with the original.
2. figure out how to add salt and pepper to the hash
I am not looking for the exact solution, but maybe some hints to get further :)
Code
function createAdmin(){
var usertypeid = null;
const type = "adm";
pool.query(`INSERT INTO usertype(type) VALUES ($1) RETURNING userTypeId;`, [type], function (error, results) {
if (error){
throw error;
} else{
usertypeid = results.rows[0].usertypeid;
console.log(usertypeid);
insertAdmin();
}
});
function insertAdmin(){
pool.query(`
INSERT INTO users(
usertypeid, userName, email, password)
VALUES($1, 'admin', 'admin#admin.com', CRYPT('admin', GEN_SALT('md5')));`, [usertypeid]);
}
}

Answer 1

As mentioned in the comments, don't use MD5 anymore as it's deprecated a long time ago.
The other thing is that hashing is different from encrypting. You can't decrypt a hash like you do with a cipher.
What should happen is that you run the plaintext through the hashing algorithm and then see if it matches the original hash computed at the beginning.
For Node.js there are good libraries out there like bcrypt which can be used to simplify the process and perhaps make it more secure.
If you insist to perform your own validation procedure, then it should be like the following:
Get the user's password from the login form
Run it through the hashing algo of your choice (no MD5 please)
Query the database for the hashed password
Compare if the hashed password from the login form is the same as the one in the DB

Answer 2

As the docs say, you want something like this (renaming table and columns to match your example):
SELECT (password = crypt('entered password', password)) AS pswmatch FROM users where username='admin';
The value stored in users.password from your insertion is a combination of the algorithm, the salt, and result of hashing the actual password with that algorithm and salt. Now you pass users.password into crypt again, so that it can extract from it the algorithm and the salt. It then uses that algorithm and salt to recompute the hash of the alleged password. If the re-computed value matches the stored value, then the alleged password is correct.