It isn't something that is taught nor should be sought after. Isn't bad either if you can't.
I know of many who can "speak in tongues" but is completely deceived and unknowingly serving the devil and end up spreading the lies of the devil instead like loving the things of this world and loving money.
Although the gift of tongues cannot be taught, seeing that it is a supernatural gift that the Holy Spirit bestows on a person, there are Scriptural steps to follow for anyone desiring spiritual gifts as well as the gift of tongues.
The first step is that one has to be totally sure that it is the will of God for them to have the gift. Christian peer pressure or church expectations are not enough. The person must be totally sure within themselves that this particular gift is what the Holy Spirit wants them to have. This certainly can come only after prayer and study of God's Word.
The next step is to ask God for the gift. "Everything by prayer and supplication, with thanksgiving, make your requests known to God." If the person has, through prayer and the study of God's Word, receives an assurance from the Holy Spirit that He will bestow the gift, then the request will be done in faith. This is not because the person believes, having his faith in what they believe, but having faith in God's promise that has come through prayer and study of God's Word.
The third step is to receive the gift. Because they know that the Holy Spirit wants to bestow the gift, and has asked for it in faith, then they can receive the gift from God's outstretched hand. "He who asks, receives". "Receive that your joy may be full." The prayer would be: "Thank you Lord. I now receive the gift of [whatever]". This is not naming and claiming. We can make no claims on God at all. We don't have that right, and it would be the height of arrogance to think we can claim things from God as our right. We receive the gift from God's hands as He extends it to us through His grace, and not because we have done anything to earn it.
The fourth step is to launch out and do what we couldn't do before. As with the gift of tongues, we try to form the language by putting together sounds and syllables. What happens is that the Holy Spirit will cause the flow of language to come up from within us. We can't say we are using the gift of tongues until there is a fluent flow of expressive, articulate language coming from within us.
A lot of what we hear through Youtube videos is not fluent articulate language. It is just a hodge podge salad of sounds. This is because it is spoken publicly without interpretation, something that Paul opposed. But when the person is engaged in prayer to the Lord, actively seeking His face, then the environment is right for the river of living water to flow out of him in an expressive, articulate language that gives them the inner witness that God is hearing and understanding what is being spoken.