1. i want to read from channel 1 to 4 how can i do it
2.i want to do in sequence how can i do it
EHILLEL820,
You absolutely can read from channel 0 to channel 3 (1-4) in sequential order. Assuming you are using the AD7091R-4, you can simply program the channel register (ADDR = 0x01) with code 0x000F to enable channels 0 to 3 for conversion.
If you meant that you are using the 8 channel, AD7091R-8 and you want to convert channels VIn1 to Vin4 then simply write 0x001E to the Channel register.
More information on device configuration can be found in the datasheet
https://www.analog.com/media/en/technical-documentation/data-sheets/AD7091R-2_7091R-4_7091R-8.pdf
starting on page 23.