The topic of the role of Native Americans in the colonial or imperial wars of the 1700s can be approached from a number of perspectives.
The most direct role was through participation in armed conflicts between imperial powers. Collectively, natives served as foot soldiers, suffering large losses. Their participation sometimes resulted from assimilation with or into the colonies. Other times, they chose to fight out of political calculation (e.g. in hopes of increased sovereignty). They often tried to play the major colonial powers off each other. As more time passed and their civilization crumbled, the involvement was frequently dictated by their position of weakness: to pay off debts or simply to have access to food and other necessities of life. While they were not powerless or passive, and they sometimes mounted major armed opposition (e.g. Pontiac's Rebellion), they often had little leverage and limited choices.
Native Americans played a substantial military role in colonial warfare. There are helpful online resources, a few of which are linked below. One should keep in mind that the relationship between Europeans, colonists, and natives was multi-faceted. Interactions could be military, financial, cultural, and so forth, with no clean lines separating one form of interaction from another. Interactions persisted over centuries with different tribal and political entities. In other words, the topic is a big one.
The Native Americans also contributed to the conflicts in less direct ways: for example, colonial forces often adopted native tactics of warfare. The natives were familiar with their home terrain and, in terms of technology and supplies, were frequently at a disadvantage. These circumstances dictated guerilla warfare. The various imperial powers used these methods to varying extent, but they were embraced on a mass scale by the British colonies and, later, American revolutionaries. One could argue that the British colonists, operating from a similar position of familiarity with the terrain and relative weakness, adopted native strategies as a means of defeating the king's armies during the American Revolution.