Under normal circumstances, there is no need to change the tone, just read the second tone normally.
In Mandarin, the situations that require tone changes include first and second tone changes, upward tone changes, falling tone changes, adjective overlapping tone changes, etc. In addition, there is another situation where there are words with double tones or words following the overlapping form in the name. At this time, the second character in the name is pronounced softly. For example, Xu Meimei is pronounced xú?méi mei.
Extended information
The detailed explanation of Mandarin tones is as follows:
1. 1. No tones
For example: All in one place, one style, one year old Piece
In this group of words, the characters after "一" are all toneless characters, and "一" all change from the original tone of Yinping (one tone) to Yangping (second tone).
2. Changes in the upper tone
When the upper tone syllable is pronounced alone or at the end of a word or sentence, the tone does not change. In addition to this, the two upper voices are connected and the previous upper voice becomes like Hinata.
3. The tone change of the falling tone
Two falling voices are connected. If the previous one is not a stressed syllable, it will become a semi-falling tone (53): the falling tone connects the previous 53
Example: Service Rapid Cooperation Conference
4. Modifications of the overlapping form of adjectives
The inflection of the overlapping form of adjectives refers to adding the ending of the adjective and the ending of the adjective after the overlapping form. Overlapping of words and changes in tone when under-reading occurs.
For example: Hao'er's, Da'er's, and slowly'er are added to the ending, and the second syllable of the overlapping style changes to Yinping tone.
Baidu Encyclopedia - Tone Change
Baidu Encyclopedia - Tone Change