The B7 (B seventh) chord is a key chord for any guitarist, especially if you plan to play the blues. It is dark and melodic, plus it can be played in various parts along the arm of the guitar.
Steps

Step 1. Make a capo on all the strings from 5
Pressing on the 2nd fret. Use your index finger to press the strings at the second fret, ignoring the E (E) string, it is the thick one at the top.
- Don't forget that the guitar strings are counted from the bottom. The thin string is the first, the thickest is the sixth.
-
Shortcut:
If you already know the chord Bm (B major), you will only have to remove one finger to get B7 (B seventh). Take your finger off the third string and let it air. Now you will have a B7 (If seventh)

Step 2. Place your ring finger on the fourth fret of the D (D) string
If you know how to form an open A7 chord (The seventh), your fingers will be in the same position. If you don't know, just use your ring finger to press the fourth fret on the third string.

Step 3. Leave 5
String, G (G), open. Simply let the capo sound on the second fret instead of pressing it too hard. Make sure you can hear the capo string cleanly.

Step 4. Step 4
° fret of string B (Si) with your little finger. This takes some practice for beginners, but is a great way to start training your fifth finger. This is the second thinnest string on the guitar. Leave the string under it, E (E) sharp, open.
Make sure your ring finger doesn't accidentally mute this string

Step 5. Strum all the strings except the sixth to play your B7 (B7)
Play all the strings from top to bottom to sound a beautiful B7 (B 7).
- --2--
- --4--
- --2--
- --4--
- --2--
- --X--

Step 6. Use your index finger to capo on an open E7 (E 7th) chord
If you know how to make the E7 (E seventh) chord in its open form, you can simply move it down the arm of the guitar to the B note (Si), make the capo and you have a B7 (B seventh). This only works for chords that start on the sixth string, but makes it easier to play a chord on its seventh anywhere on the guitar arm. Imagine that the open strings are already with a capo, they all sound being at the same "fret" in your chord. This means that your other two fingers will make any chord a barbed seventh. By having the B (B) chord at the seventh fret, the capo B7 (B) chord will look something like this:
- --7--
- --7--
- --8--
- --7--
- --9--
- --7--