The ring finger would be number 3. These chords are in standard format played near the head of the guitar. The same chords are shown below in barre format. Now the same chords shown in double bar format. This method is just to get you close to being in tune.
Nothing can replace a good electronic tuner.
All you need is to have a telephone handy. Adjust the tone of the string until you feel it is the same as the dialtone. The two strings should sound identicle. There should be little if any vibration of the 5th string. There should be little if any vibration of the 5th string.