If you don’t have a guitar tuner there are other ways to get your guitar in tune.
One solution is to tune your guitar to itself. Begin with the 1st string. Remember that this is the thinnest string. If there is a piano, a keyboard or any other instrument available to give you a reference “E” note. Match your string to that note.To tune your 1st and 2nd string together you would place a finger on the 2nd string at the 5th fret. Because this note is also “E” the pitch of the 1st string open and the 2nd string at the 5th fret should should the same. It will be the 2nd string tuner that you will be turning.
Once you’ve matched the pitch of the 1st and 2nd strings you’ll tune the 3rd string. You do this by placing a finger on the 3rd string at the 4th fret and matching it to the open 2nd string. This works because the 2nd string open is “B” and the note at the 4th frst on the 2nd string is also “B”.
Now move onto the 4th string. Place your finger on the 5th fret of the 4th string and play the 3rd string open. These notes are both “G”.
You repeat the process on the 5th string on the 5th fret open and match it to the 4th string open. Both of these notes are “D”.
Finally, to tune the 6th string you would play the 6th string at the 5th fret and match it to the 5th string open. Both of these notes are “A”.
If you matched all of the notes your guitar will be in tune.
Remember that the strings are E, B, G, D, A, E beginning with the thinnest string first.
Tuning is a learned thing. It takes practice and as you do it successfully you’ll gain more confidence.