Use the buttons on a touch screen or the home row keys on your keyboard.
Numeric character set (initial; back with L1+R1): 0: L1; 1: R0; 2: R1; 3: R2; 4: L0; 5: L0+R0; 6: L0+R1; 7: L0+R2; 8: L2+R0; 9: L2+R1; Backspace: L1+R0; Space: L2; New line: L2+R2
Alphabetic (A-J + N, O, U) character set (L1+R1): A: R0; B: L0+R0; C: L0+R1; D: L0+R2; E: L1; F: L1+R0; G: L2; H: L2+R1; J: L2+R2; N: L0; O: L1; U: L2
Alphabetic (K-) character set (L1+R2): K: R0; L: R1; M: R2; P: L0; Q: L0+R0; R: L0+R1; S: L0+R2; T: L1; V: L1+R0; W: L1+R1; X: L2; Y: L2+R1; Z: L2+R2