When you want to say 'I'm looking for ...' in Chinese, you can say '我在找...' -- wǒ zài zhǎo

我 (wǒ) means I在 (zài) means the present tense, doing
找 (zhǎo) means look for

Tom is written as 汤姆 in simplified Chinese. Its pronunciation is tāng mǔ
John is written as 约翰 in simplifed Chinese. Its pronunciation is yuē hàn, which is quite different as the English pronunciation.

'I'm looking for Tom' is 我在找汤姆 (wǒ zài zhǎo tāng mǔ )