I want to make I2C communication between attiny10 and BMA400, I feel lost at the moment and not very experienced. If I could get some suggestions for where to begin, what to learn, or if you have some tutorial on the internet that you know I would be really greatful.
thanks
You can try a search foor "Arduino + I2C" and start looking at bit at things. Get introduced to I2C.
Usually the perferal, like the BMA400 uses some library made for the communication via the bus.
BMA400 sensor uses I2C bus for communication. Does ATtiny10 MCU support I2C Bus (Fig-1)? If not, then switch to ATtiny85 which supports I2C Bus and has a fantastic development platform -- the Digispark Attiny85 Dev Board (Fig-2).
Figure-1:

Figure-2:
You can start with this I2C oled demonstration. It implements I2C via bitbanging. Works on the Attiny10 also.