"I am Raj."
Translation:मैं राज हूँ।
ं (called Bindu (dot) or Anusvaar) stands for a nasal consonant. It has to be pronounced like one of Hindi's five nasal consonants (ङ, ञ़, ण, न and म). For example, हिंदी is pronounced 'Hindi' where the ं is pronounced as न(n). Similarly, लंबा (tall) is pronounced 'Lamba' where the ं is pronounced as म(m). Which of the five nasal consonants it is pronounced as in a particular word depends on the letter that follows.
ँ (called Chandrabindu (moon-dot) or Anunaasik) stands for vowel nasalisation. When it is present in a word, you try to make the vowel sound with your nose as well as your mouth. For example, in माँ, the vowel is आ. The 'aa' sound should come from both your nose and mouth.
In some words, where there is no space above the horizontal line to put the ँ because of the other diacritic marks, we use the ं in its place with the understanding that we still want to nasalise the vowel. For example, में (in) where we should nasalise the ए vowel.
I found that on my Mac, using Keyboard Preference and adding Hindi – QWERTY as the Input Source, I can get a ॅ by pressing 'q' and if I then press Shift m ं it adds them to form ॅं which is the chandrabindu. What do you see on your phone?
Note that you then need to add a space afterwards so it registers that you have finished constructing the syllable—or DL flags it as an error.
[See Vinay's solution below! Use option + m]