How to I make people talk with ClickEvent books in minecraft?

Here is a command that will do that:

/give @p written_book 1 0 {pages:["[\"\",{\"text\":\"Click Here\",\"color\":\"blue\",\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/say Hello There\"}}]"],title:"Hello there",author:IronAnvil}

Though, I recommend using a book editor tool if you want more complications as formatting is tough. Here is the one I used for that command.

Add a clickEvent that runs a command and use the say command.

If you want to see a little bit more complication, here is another command. This one is long enough it will need to be run from a command block:

/give @p written_book 1 0 {pages:["[\"\",{\"text\":\"Hello there:\\n\"},{\"text\":\"Click here\",\"color\":\"blue\",\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/say Hello there\"},\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"If you click here, you will say 'Hello there' in chat.\"}},{\"text\":\"\\n\\nGoodbye:\\n\",\"color\":\"reset\"},{\"text\":\"Click Here\",\"color\":\"red\",\"clickEvent\":{\"action\":\"run_command\",\"value\":\"/say Goodbye\"},\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"If you click here, you will say 'Goodbye' in chat.\"}},{\"text\":\"\\n\",\"color\":\"reset\"}]"],title:"Book of Speak",author:IronAnvil}

Edit:

Here are both commands again but the clickEvent does not specify a command so it just outputs to chat:

/give @p written_book 1 0 {pages:["[\"\",{\"text\":\"Click Here\",\"color\":\"blue\",\"clickEvent\":{\"action\":\"run_command\",\"value\":\"Hello There\"}}]"],title:"Hello there",author:IronAnvil}

/give @p written_book 1 0 {pages:["[\"\",{\"text\":\"Hello there:\\n\"},{\"text\":\"Click here\",\"color\":\"blue\",\"clickEvent\":{\"action\":\"run_command\",\"value\":\"Hello there\"},\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"If you click here, you will say 'Hello there' in chat.\"}},{\"text\":\"\\n\\nGoodbye:\\n\",\"color\":\"reset\"},{\"text\":\"Click Here\",\"color\":\"red\",\"clickEvent\":{\"action\":\"run_command\",\"value\":\"Goodbye\"},\"hoverEvent\":{\"action\":\"show_text\",\"value\":\"If you click here, you will say 'Goodbye' in chat.\"}},{\"text\":\"\\n\",\"color\":\"reset\"}]"],title:"Book of Speak",author:IronAnvil}