In your concept, the Tasks table is the linking table:
Tasks (task_ID, task_name, task_starttime, project_ID, employee_ID, task_competion -using a timedate stamp)
The project_ID columns creates a many to many relation for the main table Projects.project_ID column
and the employee_ID column creates a many to many relation for the option table Employees.employee_ID
NOTE: While it is entirely up to you, It's a good idea to use a naming convention for your columns that prevents duplicate names. also, using underscores in the column names can cause issues in Dreamweaver, I prefer and recommend to use the camelCase naming convention instead.
The naming convention i like to use is to include the table name as a prefix to the column names. you are pretty much already doing this, with the exception of the foreign key columns in the tasks table. For example, the naming convention I would use for your tables is;
projects (projectID, projectName)
tasks (taskID, taskName, taskStarttime, taskProjectID, taskEmployeeID, taskCompletion)
employees (employeeID, employeeName, employeeEmail, employeePassword)
by using taskProjectID and taskEmployeeID as the name in the tasks table, there is no way to confuse them with the projects.projectID or employees.employeeID primary key columns. this can helpful when working with a big recordset that joins many tables together.