How do I get WiFi in a large outdoor area?

Can you explain the steps I should take to establish WiFi connectivity in a vast outdoor space? Are there specific hardware requirements, such as routers or antennas, that are essential for covering a broad area? Additionally, what considerations should I make regarding signal strength, security, and the number of devices that will be connected? Is there a need for professional installation, or can I handle it myself with the right tools and guidance? Also, are there any cost-effective solutions that can help me achieve reliable WiFi coverage in my outdoor area?